A 20-year decline in male circumcision has cost the country $2 billion in medical costs that could have been prevented, Johns Hopkins researchers say in a study released Monday.

In what is believed to be the first look at the economic impact of male circumcision on the health care system, the Hopkins scientists say that boys who are not circumcised are more prone to sexually transmitted diseases and other health problems over a lifetime that are costly to treat.

"The economic evidence is backing up what we already know medically," said Dr. Aaron Tobian, a Hopkins health epidemiologist and pathologist and senior researcher on the study.

The findings are the latest in a continuing debate over the health benefits of a procedure that was once common practice in the United States — and comes as the Academy of American Pediatrics prepares to announce updated guidelines on male circumcision next week.

Circumcision became controversial in the 1970s when the rate of procedures began to decline. Today, about 55 percent of the 2 million baby boys born each year are circumcised, compared with a peak of 79 percent in the 1970s and 1980s.

The Academy of American Pediatrics, which advises doctors on medical procedures, has taken a neutral stance on the issue for years. It last updated its position in 2005, reaffirming a stance from 1999 that there wasn't enough scientific evidence to show medical benefit to recommend circumcision.

Studies have long shown that when babies are not circumcised, where the foreskin on the tip of the penis is removed, they are at risk for health problems in the long run. Bacteria and viruses can get trapped in the extra layers of skin left on the penis.

Research has found that circumcision reduces the number of infant urinary tract infections. Men who are uncircumcised are more at-risk for cancer-causing HPV, HIV, herpes, bacterial vaginitis and other sexually transmitted diseases, studies have found.

The Hopkins researchers, who published their results online in the Archives of Pediatrics & Adolescent Medicine, say the cost to treat these long-term health problems is putting extra financial strain on the medical system. The majority of the costs are in the treatment of HIV, the study found.

Opponents of circumcision say that it is a painful, unnatural procedure that in the long term results in decreased sexual pleasure and in psychological problems. They point to studies that debunk the link to sexually transmitted diseases and criticized the latest findings by Hopkins.

"To totally ignore all the harm circumcision does and say we're going to save money is a limited and distorted view of what this is all about," said Ronald Goldman, executive director of the Circumcision Research Center in Boston.

Ryan McAllister, a biophysicist at Georgetown University and coordinator at Takoma Park-based NotJustSkin.org, argues that medical costs rise when babies are circumcised. He said many boys need operations to correct botched circumcisions and may suffer emotional duress. He said circumcision is no more than a cosmetic surgery.

"People forget it is a child's penis you are operating on," McAllister said. "They said it's just a snip when it is much more."

The push for circumcision has gained an international platform as a way to prevent the spread of HIV in Africa after several studies showed infection rates decreased rapidly. The area beneath the foreskin of the penis is believed to have a higher density of target cells for HIV.

In America, support has been declining for circumcision, a ritual for years performed for cultural, medical and religious reasons. Some families are choosing to forgo the procedure for personal reasons. Eighteen states have stopped paying for babies of poor families to have the procedure under Medicaid. Maryland is not among those states.

The Hopkins researchers think the drop in coverage is contributing to the long-term rise in medical costs as states seek short-term savings. State Medicaid plans account for two-fifths of all births. A circumcision costs on average $254, which may seem expensive to a family trying to make ends meet.

The Hopkins analysis found that when a male is not circumcised it costs $313 more in medical expenses to treat conditions he would not otherwise have suffered.

The researchers said that if male circumcision rates dropped to those in Europe, where 10 percent of male babies get the procedure, there would be a 12 percent increase in men infected with HIV and 29 percent in those who contract HPV.

A European rate of circumcision in the United States could add $4.4 billion in avoidable medical costs in the next decade, the Hopkins study found.

The Hopkins researchers hope to use their findings to support a push for more funding and acceptance of the procedure. The research dovetails with a push to encourage the federal Medicaid program to mandate payment for circumcision rather than leave it optional for states. They want private insurance to cover the procedure as well.

"I think all barriers for male circumcision should be removed," Tobian said.

Some doctors said more needs to be done to make people aware of the benefits of circumcision and that the Hopkins study could help.

He said he has seen infections in men who are uncircumcised and who may not clean under the folds of the skin well enough. Some men get conditions where the foreskin tightens or scars and won't move. Lerner has recommended circumcision in older patients who have health issues.

He agreed with the Hopkins researchers that states should fund circumcisions.

"If you have a population that takes care of themselves, that does perform excellent hygiene and performs safe sexual practices, they will have lower risk," Lerner said. "We're talking more about Medicaid population which may not be as health-conscious, and that is a concern."

Dr. Richard Colgan of the University of Maryland School of Medicine said he leaves the decision of circumcision up to the parents.

"Certainly, I don't think this is a slam-dunk, carte blanche to now strong-arm parents to get their children circumcised," said Colgan, an associate professor and a doctor in family medicine. "It is one of several pieces of information that can be used by families to make the decision that is right for them."